Princess Peach is trapped in one of the four corners of a square grid. You are in the center of the grid and can move one step at a time in any of the four directions. Can you rescue the princess?
Input format
The first line contains an odd integer N (3 <= N < 100) denoting the size of the grid. This is followed by an NxN grid. Each cell is denoted by '-' (ascii value: 45). The bot position is denoted by 'm' and the princess position is denoted by 'p'.
Grid is indexed using Matrix Convention
Output format
Print out the moves you will take to rescue the princess in one go. The moves must be separated by '\n', a newline. The valid moves are LEFT or RIGHT or UP or DOWN.
Here is my code:
package challenges;
import java.util.*;
public class Solution {
static void displayPathtoPrincess(int n, int p,String [][] grid){
int botRow=0,botCol=0;
for(int r=0;r<n;r++){
for (int c = 0; c < grid.length; c++) {
if(grid[r][c].equals('m')) {
botRow=r;
botCol=c;
continue;
}
}
if(grid[0][0].equals('P')) {
while(botRow>0) {
botRow--;
System.out.println("UP\n");
}
while(botCol>0) {
botCol--;
System.out.println("LEFT\n");
}
}
else if(grid[0][p-1].equals('P')) {
while(botRow>0) {
System.out.println("UP\n");
botRow--;
}
while(botCol<p-1) {
botCol++;
System.out.println("RIGHT\n");
}
}
else if(grid[n-1][0].equals('P')) {
while(botRow<n-1) {
botRow++;
System.out.println("DOWN\n");
}
while(botCol>0) {
botCol--;
System.out.println("LEFT\n");
}
}
else if(grid[n-1][p-1].equals('P')) {
while(botRow<n-1) {
botRow++;
System.out.println("DOWN\n");
}
while(botCol<p-1) {
botCol++;
System.out.println("RIGHT\n");
}
}
}
}
public static void main(String[] args) {
Scanner in = new Scanner(System.in);
int m,n;
m = in.nextInt();
n=m;
int j=0;
String grid[][] = new String[m][n];
for(int i = 0; i < m; i++) {
while(j<n){
grid[i][j] = in.next();
j++;
}
}
displayPathtoPrincess(m,n,grid);
}
}
Its giving Null Pointer Exception.can anyone please tel what am i doing wrong in here?
Try this solution:
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
public class Solution
{
public static void main(String[] args) throws IOException
{
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
int m = Integer.parseInt(br.readLine());
char grid[][] = new char[m][m];
for(int i = 0; i < m; i++)
{
String line = br.readLine();
grid[i] = (line.trim()).toCharArray();
}
displayPathtoPrincess(m, grid);
}
static void displayPathtoPrincess(int m, char[][] grid)
{
int botRow = 0, botCol = 0, princessRow = 0, princessCol = 0;
// Get bot and princess coordinates
for (int r = 0; r < m; r++)
{
for (int c = 0; c < grid.length; c++)
{
if (grid[r][c] == 'm' || grid[r][c] == 'M')
{
botRow = r;
botCol = c;
}
else if (grid[r][c] == 'p' || grid[r][c] == 'P')
{
princessRow = r;
princessCol = c;
}
}
}
// Move the bot up or down till bot reaches same row
if( princessRow < botRow )
{
while(botRow != princessRow)
{
botRow--;
System.out.println("UP");
}
}
else if( princessRow > botRow )
{
while(botRow != princessRow)
{
botRow++;
System.out.println("DOWN");
}
}
// Move the bot left or right till bot reaches same column
if( princessCol < botCol )
{
while(botCol != princessCol)
{
botCol--;
System.out.println("LEFT");
}
}
else if( princessCol > botCol )
{
while(botCol != princessCol)
{
botCol++;
System.out.println("RIGHT");
}
}
}
}
Ok, no offence but this code is a mess.
I know what I will answer won't be exactly what you want, but it might be very helpful for you in the future.
What would I change? (After you change all of this, the error will more likely become apparent or it will be clear enough to ask for help)
First: Variable types.
This is just a tiny detail, but I don't like the way you did it; why use a String if every cell will be represented by a char?
Every time you create a variable (or an Array, or anything at all) think about what you need it to store, and create the variable in a way it will store what you need. If you needed it to store if something is true or false, you wouldn't create a String variable and store "true" or "false", you would use a boolean.
Apply this every time and you will improve faster.
Second: use functions.
Functions are a great way to abstract yourself from the implementation details.
I mean, you can easily see the difference between something like your code, and something like:
static void displayPathtoPrincess(int n, int p,char [][] grid){
Point bot;
Point princess;
getInitialPositions(bot, princess, grid);
Point dif = getRelativePrincessPosition(bot, princess);
while (!bot.equals(princess)) {
switch (dif.y) {
case UP:
move (UP_MOVEMENT);
break;
case DOWN:
move (DOWN_MOVEMENT);
break;
}
switch (dif.x) {
case LEFT:
move(LEFT_MOVEMENT);
break;
case RIGHT:
move(RIGHT_MOVEMENT);
break;
}
}
}
(And then implement the necessary methods, and create the constants, that is something pretty easy to do)
Third: use the appropriate loop every time.
If you know you want to go from j = 0, while j < n, increasing j every iteration; that's not called a while, that's called a for. (Also, as someone else commented in their answer, you forgot to restart the j; so it only goes in once.
Finally: Let's go with your error now.
I believe your code might be pretty buggy and not give you the desired output, but the NullPointerException is something more specific.
Since you don't use the appropriate loop in the main, for j, and you forgot to restart it's value, you didn't fill the whole array.
When you try to read a value you didn't fill (in the for where you find the robot's position), that value is null, and the value for some rows will be null too; hence the NullPointerException (because you try to access the value of a null array).
While taking input you have to make j =0 every time you are coming out of while loop as
public static void main(String[] args) {
Scanner in = new Scanner(System.in);
int m,n;
m = in.nextInt();
n=m;
int j=0;
String grid[][] = new String[m][n];
for(int i = 0; i < m; i++) {
j = 0;
while(j<n){
grid[i][j] = in.next();
j++;
}
}
i remains 0 due to this mistake.
You should put print statement to check why are you getting error.
here is the solution..
import java.util.*;
public class Solution {
static void displayPathtoPrincess(int n, int p, String[][] grid) {
int botRow = 0, botCol = 0;
for (int r = 0; r < n; r++) {
for (int c = 0; c < grid.length; c++) {
if (grid[r][c].equalsIgnoreCase("m")) {
botRow = r;
botCol = c;
}
}
if (grid[0][0].equalsIgnoreCase("P")) {
while (botRow > 0) {
botRow--;
System.out.println("UP\n");
}
while (botCol > 0) {
botCol--;
System.out.println("LEFT\n");
}
} else if (grid[0][p - 1].equalsIgnoreCase("P")) {
while (botRow > 0) {
botRow--;
System.out.println("UP\n");
}
while (botCol < p - 2) {
botCol++;
System.out.println("RIGHT\n");
}
} else if (grid[n - 1][0].equalsIgnoreCase("P")) {
while (botRow < n - 2) {
botRow++;
System.out.println("DOWN\n");
}
while (botCol > 0) {
botCol--;
System.out.println("LEFT\n");
}
} else if (grid[n - 1][p - 1].equalsIgnoreCase("P")) {
while (botRow < n - 2) {
botRow++;
System.out.println("DOWN\n");
}
while (botCol < p - 2) {
botCol++;
System.out.println("RIGHT\n");
}
}
}
}
public static void main(String[] args) {
Scanner in = new Scanner(System.in);
int m,n;
m = in.nextInt();
int j;
String grid[][] = new String[m][m];
for(int i = 0; i < m; i++) {
for(j=0;j<m;j++){
grid[i][j] = in.next();
}
}
displayPathtoPrincess(m,m,grid);
}
}
import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;
public class Solution {
static void nextMove(int n, int r, int c, String [] grid){
int xcord=0;
int ycord=0;
for ( int i = 0 ; i <n-1; i++){
String s = grid[i];
xcord=i;
for(int x =0; x<=n-1;x++){
if(s.charAt(x)=='p'){
ycord=x;
if(xcord==r){
if(ycord>c){System.out.println("RIGHT");return;}
else {System.out.println("LEFT");return;}
}else if(xcord<r){System.out.println("UP");return;}
else{ System.out.println("DOWN");return;}
}
}
}
System.out.println(xcord);
System.out.println(ycord);
}
public static void main(String[] args) {
Scanner in = new Scanner(System.in);
int n,r,c;
n = in.nextInt();
r = in.nextInt();
c = in.nextInt();
in.useDelimiter("\n");
String grid[] = new String[n];
for(int i = 0; i < n; i++) {
grid[i] = in.next();
}
nextMove(n,r,c,grid);
}
}
You might wish to take a look at the following code in Java:
import java.util.Scanner;
public class Solution {
/*
*
*/
static void printPath(int n, String moves) {
for (int i = n / 2; i >= 0; i -= 2) {
System.out.println(moves);
}
}
/*
*
*/
static void displayPathtoPrincess(int n, String [] grid){
// **** princess # top left ****
if (grid[0].substring(0, 1).equals("p")) {
printPath(n, "UP\nLEFT");
}
// **** princess # top right ****
else if (grid[0].substring(n - 1, n).equals("p") ) {
printPath(n, "UP\nRIGHT");
}
// **** princess # bottom right ****
else if (grid[n - 1].substring(n - 1, n).equals("p")) {
printPath(n, "DOWN\nRIGHT");
}
// **** princess # bottom left ****
else {
printPath(n, "DOWN\nLEFT");
}
}
/*
* Test code
*/
public static void main(String[] args) {
Scanner in = new Scanner(System.in);
int m;
m = in.nextInt();
String grid[] = new String[m];
for(int i = 0; i < m; i++) {
grid[i] = in.next();
}
// **** ****
in.close();
// **** ****
displayPathtoPrincess(m,grid);
}
}
I'm working on an assignment that takes a data file with a number matrix and determines if it is a magic square. If it is then it also needs to report the sum of the rows and columns. With the output:
The matrix is a magic square.
The sum of all the rows and columns is 34.
I'm not sure how to go about this with one method, I feel like its asking me to return 2 values. The closest I have came is by adding a System.out.println with the sum at the end of my method when it returns true.
But the issue with that is that my output is backwords:
The sum of all the rows and columns is 34.
The matrix is a magic square.
How do I get the sum when I've only been asked to create one method? Below is my code, the instructor gave the bottom 3 methods so I'm only concerned with the first 2.
import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;
public class chp8magic
{
public static void main(String args[])
{
int matrix[][] = initMatrix();
printData(matrix);
if (isMagic(matrix)) {
System.out.println("The matrix is a magic square.");
}
else {
System.out.println("Not a magic square");
}
}
public static boolean isMagic(int[][] mat)
{
int n = mat.length;
int nSquare = n*n;
int M = (n*n*(n*n+1)/2)/n;
int sumRow = 0, sumColoumns = 0, sumPriDiag = 0, sumSecDiag = 0;
boolean[] flag = new boolean[n*n];
for(int row = 0; row < n; row++){
sumRow = 0;
sumColoumns = 0;
for(int col = 0; col < n; col++)
{
if( mat[row][col] < 1 || mat[row][col] > nSquare )
return false;
if(flag[mat[row][col]-1] == true)
return false;
flag[mat[row][col]-1] = true;
sumRow += mat[row][col];
sumColoumns += mat[col][row];
}
sumPriDiag += mat[row][row];
sumSecDiag += mat[row][n-row-1];
if(sumRow!=M || sumColoumns!=M)
return false;
}
if(sumPriDiag!=M || sumSecDiag!=M)
return false;
else
return true;
}
public static int[][] initMatrix()
{
int matrix[][];
Scanner filein = null;
try {
filein = new Scanner(new File("matrix.txt"));
int numRows = Integer.parseInt(filein.nextLine());
matrix = new int[numRows][];
parseData(matrix, filein);
filein.close();
return matrix;
} catch (FileNotFoundException e) {
System.out.println(e.getMessage());
if(filein != null)
filein.close();
return null;
}
}
public static void parseData(int matrix[][], Scanner in)
{
for(int r = 0; r < matrix.length; r++)
{
String splitLine[] = in.nextLine().split(" ");
matrix[r] = new int[splitLine.length];
for(int c = 0; c < matrix[r].length; c++){
matrix[r][c] = Integer.parseInt(splitLine[c]);
}
}
}
public static void printData(int matrix[][])
{
for(int r = 0; r < matrix.length; r++){
for(int c = 0; c < matrix[r].length; c++){
System.out.print(matrix[r][c] + " ");
}
System.out.println();
}
}
}
Probably you just need to do:
System.out.println("is magic: " + isMagic);
System.out.ptintln("sum: " + sum);
However this is not really returning the values, just printing them. To return two values there are several options. You could return an object:
public class MagicSquareProperties {
private boolean magic;
private int sum;
public MagicSquareProperties(boolean magic, int sum) {
this.magic = magic;
this.sum = sum;
}
public boolean isMagic() {
return magic;
}
public int getSum() {
return sum;
}
}
// now to return both values: return new MagicSquareProperties(true, 34);
But in my opinion the best solution would be the following:
Create a class MagicSquare.
Add property declarations (e.g. private int sum).
Add a constructor, for example MagicSquare(File file), this constructor reads the file and populates the properties.
Add getters and setters if needed (e.g. getSum())
Execute the main method in another class and call new MagicSquare(...) to create a magic square object. Afterwards you can call the getters on the object whenever you need the value.
I am new to Java and I needed dynamic Array ... all of thing I found that's for dynamic Array we should use "Array List' that's ok but when I want the indexes to be the power of X that given from input , I face ERORR ! .. the indexes are unclear and the are not specified what is the first or 2th power ! .... can anyone help me how solve it?
public static void main(String[] args) throws Exception {
Scanner Reader = new Scanner(System.in);
ArrayList<Float> Zarayeb = new ArrayList<Float>();
Float s ;
int m;
System.out.print("Add Count of equation Sentences : ");
int N = Reader.nextInt();
if (N == 0)
return;
for (int i = 0; i < N ; i++) {
s = Reader.nextFloat() ;
System.out.print("x^");
m = Reader.nextInt();
if (Zarayeb.get(m)== null)
Zarayeb.add(0 , s);
else{
Float l ;
l = Zarayeb.get(m);
Zarayeb.add (m , l+s);
}
if (i < N-1)
System.out.print("\r+");
}
System.out.print("Add Count of equation Sentences : ");
N = Reader.nextInt();
if (N == 0)
return;
for (int i = 0; i < N ; i++) {
s = Reader.nextFloat() ;
System.out.print("x^");
m = Reader.nextInt();
if (Zarayeb.get(m)== null)
Zarayeb.add(m , s);
else{
Float l ;
l = Zarayeb.get(m);
Zarayeb.add (m , l+s);
}
if (i < N-1)
System.out.print("\r+");
}
System.out.print("Enter X: ");
float X = Reader.nextFloat();
float Sum = 0;
for (int i = 0; i < Zarayeb.size();i++) {
Sum += (Zarayeb.get(i) * Math.pow(X,i));
}
System.out.println("\nThe final answer is : " + Sum);
First I refactored your code a bit to make sense of it:
Main class with the top level logic:
import java.util.Scanner;
public class Main {
private Scanner scanner;
private final Totals totals = new Totals();
public static void main(final String[] args) {
final Main app = new Main();
app.run();
}
private void run() {
scanner = new Scanner(System.in);
try {
readAndProcessEquationSentences();
} finally {
scanner.close();
}
}
private void readAndProcessEquationSentences() {
readSentences(true);
readSentences(false);
System.out.println("The final answer is : " + totals.calculateSum(readBaseInput()));
}
private void readSentences(final boolean useInitialLogic) {
System.out.print("Enter number of equation sentences:");
final int numberOfSentences = scanner.nextInt();
if (numberOfSentences == 0) {
throw new RuntimeException("No sentences");
}
for (int i = 0; i < numberOfSentences; i++) {
Sentence sentence = Sentence.read(scanner);
if (useInitialLogic) {
totals.addInitialSentence(sentence);
} else {
totals.addNextSentence(sentence);
}
if (i < numberOfSentences - 1) {
System.out.print("\r+");
}
}
}
private float readBaseInput() {
System.out.print("Enter base: ");
return scanner.nextFloat();
}
}
Sentence class which represents one equation sentence entered by the user:
import java.util.Scanner;
public class Sentence {
private Float x;
private int y;
public static Sentence read(final Scanner scanner) {
final Sentence sentence = new Sentence();
System.out.println("Enter x^y");
System.out.print("x=");
sentence.x = scanner.nextFloat();
System.out.println();
System.out.print("y=");
sentence.y = scanner.nextInt();
System.out.println();
return sentence;
}
public Float getX() {
return x;
}
public int getY() {
return y;
}
}
Totals class which keeps track of the totals:
import java.util.ArrayList;
import java.util.List;
public class Totals {
private final List<Float> values = new ArrayList<Float>();
public void addInitialSentence(final Sentence sentence) {
if (values.size() <= sentence.getY()) {
addToStart(sentence);
} else {
addToValue(sentence);
}
}
private void addToStart(final Sentence sentence) {
values.add(0, sentence.getX());
}
public void addNextSentence(final Sentence sentence) {
if (values.size() <= sentence.getY()) {
values.add(sentence.getY(), sentence.getX());
} else {
addToValue(sentence);
}
}
private void addToValue(final Sentence sentence) {
Float total = values.get(sentence.getY());
total = total + sentence.getX();
values.add(sentence.getY(), total);
}
public float calculateSum(final float base) {
float sum = 0;
for (int i = 0; i < values.size(); i++) {
sum += (values.get(i) * Math.pow(base, i));
}
return sum;
}
}
I don't have the foggiest idea what this is supposed to do. I named the variables according to this foggy idea.
You are letting the user input values in two separate loops, with a slightly different logic I called 'initial' and 'next'.
In the initial loop you were doing this:
if (Zarayeb.get(m) == null)
Zarayeb.add(0 , s);
In the next loop this:
if (Zarayeb.get(m) == null)
Zarayeb.add(m , s);
There are problems with this because the ArrayList.get(m) will throw an IndexOutOfBoundException if m is out or range. So I changed that to the equivalent of:
if (Zarayeb.size() <= m) {
....
}
However, in the 'next' case this still does not solve it. What should happen in the second loop when an 'm' value is entered for which no element yet exists in the ArrayList?
Why do you need to enter sentences in two loops?
What is the logic supposed to achieve exactly?
The program I am working on is a simple shipping program. What I am having difficulty with is populating a multidimensional array factoring in certain variables.
Example
320 items need to be shipped out to 1 receiver using different box sizes.
XL can hold 50 items
LG can hold 20 items
MD can hold 5 items
SM can hold 1 items
Use the least number of boxes so far.
Code
This is my code so far.
import java.util.Scanner;
public class Shipping {
public static void main(String [] args) {
Scanner kbd = new Scanner(System.in);
final int EXTRA_LARGE = 50;
final int LARGE = 20;
final int MEDIUM = 5;
final int SMALL = 1;
String sBusinessName = "";
int iNumberOfGPS = 0;
int iShipmentCount = 0;
displayHeading(kbd);
iShipmentCount = enterShipments(kbd);
int[][] ai_NumberOfShipments = new int [iShipmentCount][4];
String[] as_BusinessNames = new String [iShipmentCount];
for (int iStepper = 0; iStepper < iShipmentCount; iStepper++) {
sBusinessName = varifyBusinessName(kbd);
as_BusinessNames[iStepper] = sBusinessName;
iNumberOfGPS = varifyGPS(kbd);
calculateBoxes(ai_NumberOfShipments[iStepper],iNumberOfGPS, EXTRA_LARGE, LARGE, MEDIUM, SMALL);
}
//showArray(as_BusinessNames);
}
public static void displayHeading(Scanner kbd) {
System.out.println("Red River Electronics");
System.out.println("Shipping System");
System.out.println("---------------");
return;
}
public static int enterShipments(Scanner kbd) {
int iShipmentCount = 0;
boolean bError = false;
do {
bError = false;
System.out.print("How many shipments to enter? ");
iShipmentCount = Integer.parseInt(kbd.nextLine());
if (iShipmentCount < 1) {
System.out.println("\n**Error** - Invalid number of shipments\n");
bError = true;
}
} while (bError == true);
return iShipmentCount;
}
public static String varifyBusinessName(Scanner kbd) {
String sBusinessName = "", sValidName = "";
do {
System.out.print("Business Name: ");
sBusinessName = kbd.nextLine();
if (sBusinessName.length() == 0) {
System.out.println("");
System.out.println("**Error** - Name is required\n");
} else if (sBusinessName.length() >= 1) {
sValidName = sBusinessName;
}
} while (sValidName == "");
return sValidName;
}
public static int varifyGPS(Scanner kbd) {
int iCheckGPS = 0;
int iValidGPS = 0;
do {
System.out.print("Enter the number of GPS receivers to ship: ");
iCheckGPS = Integer.parseInt(kbd.nextLine());
if (iCheckGPS < 1) {
System.out.println("\n**Error** - Invalid number of shipments\n");
} else if (iCheckGPS >= 1) {
iValidGPS = iCheckGPS;
}
} while(iCheckGPS < 1);
return iValidGPS;
}
public static void calculateBoxes(int[] ai_ToFill, int iNumberOfGPS) {
for (int iStepper = 0; iStepper < ai_ToFill.length; iStepper++)
}
//public static void showArray( String[] ai_ToShow) {
// for (int iStepper = 0; iStepper < ai_ToShow.length; iStepper++) {
// System.out.println("Integer at position " + iStepper + " is " + ai_ToShow[iStepper]);
// }
//}
}
Change your definition of calculateBoxes() to also take an array that represents the volume of each of the boxes (in your case this will be {50, 20, 5, 1}:
public static void calculateBoxes(int[] ai_ToFill, int[] boxVolumes, int iNumberOfGPS) {
// for each box size
for (int iStepper = 0; iStepper < ai_ToFill.length; iStepper++) {
// while the remaining items to pack is greater than the current box size
while(iNumberOfGPS >= boxVolumes[iStepper]) {
// increment the current box type
ai_ToFill[iStepper]++;
// subtract the items that just got packed
iNumberOfGPS -= boxVolumes[iStepper];
}
}
}
Another way of calculating this (using / and % instead of a while loop) would be:
public static void calculateBoxes(int[] ai_ToFill, int[] boxVolumes, int iNumberOfGPS) {
// for each box size
for (int iStepper = 0; iStepper < ai_ToFill.length; iStepper++) {
if(iNumberOfGPS >= boxVolumes[iStepper]) {
// calculate the number of boxes that could be filled by the items
ai_ToFill[iStepper] = iNumberOfGPS/boxVolumes[iStepper];
// reset the count of items to the remainder
iNumberOfGPS = iNumberOfGPS%boxVolumes[iStepper];
}
}
}
This is my homework(assignment). I really hope someone can help me figure out what I did wrong.
When I tried to create an object of State
state = new State(tablesize, tb);
and then tried to make a copy
State st2 = new State(state);
and then tried to modify the data in state
state.placeNumber(1,1,3);
for some reason, the data in st2 is also changed.
Below is the code. I really hope someone can point out where my mistake is.
Thanks
public class State
{
private int arraysize;
private int lastfilledx;
private int lastfilledy;
private int table[][];
//constructor
public State()
{
}
public State(State s)
{
arraysize = s.getsize();
lastfilledx = s.lastindex_x();
lastfilledy = s.lastindex_y();
table = s.gettable();
}
public State(int size, int[][] tb)
{
arraysize = size;
table = new int[size][size];
//copy the initial table which is a 2d array
table = tb;
for (int i = 0 ; i < size; i++)
{
for(int j = 0 ; j < size ; j++)
{
if ( table[i][j] == 1)
{
lastfilledx = i;
lastfilledy =j;
break;
}
}
}
}
public void placeNumber(int i, int j, int nextvalue)
{
lastfilledx = i;
lastfilledy = j;
table[i][j] = nextvalue;
}
public void printoutput()
{
for (int i=0; i < arraysize; i++)
{
for (int j=0; j < arraysize; j++)
System.out.print(" " + table[i][j]);
System.out.println("");
}
System.out.println("last fill " + lastfilledx + " " + lastfilledy);
}
public int[][] gettable()
{
return table;
}
public int getsize()
{
return arraysize;
}
public int lastindex_x()
{
return lastfilledx;
}
public int lastindex_y()
{
return lastfilledy;
}
}
public class Dikuho extends State
{
private static State state;
public static void main(String[] args) {
int tablesize = 3;
int tb[][] = new int[tablesize][tablesize];
/*****HARDCODE the table data***/
for (int i=0; i < tablesize; i++)
for (int j=0; j < tablesize; j++)
tb[i][j] = 0;
//test case for 3x3
tb[2][2] = 1;
tb[0][0] = tablesize*tablesize;
tb[0][1] = 7;
tb[1][0] = 8;
tb[2][1] = 2;
//initialize the state
state = new State(tablesize, tb);
**//Here is where the problem is. I only change the data in state but the data in st2 is also changed. I'm not sure what happen here.**
State st2 = new State(state);
state.placeNumber(1,1,3);
st2.printoutput(); **//These both printout same output which is not correct**
state.printoutput();
}
}
Your copy constructor has made a shallow copy of table 2D array. Both the original object and the copy refer to the same original array, because you assign the array reference from the original to the new object. That's fine for the int values, because the values are copied. But that's not okay for objects, for which references to the obejct are copied.
Instead of just copying the reference to the array...
table = s.gettable();
You'll need to create a new, copied array:
table = new int[arraysize][arraysize];
// 2 nested for loops here to copy the contents
public int[][] gettable()
{
return table;
}
So, both of your state objects are referencing the same array. you need to create a new array for each instance.